Final answer:
The pacemaker potential is a unique feature of pacemaker cells, which generates spontaneous action potentials to control the heart rate. These cells, such as those in the SA node, are influenced by the autonomic nervous system and hormones to modulate heart rate in response to the body's demands.
Step-by-step explanation:
The pacemaker potential refers to the capacity of certain specialized cardiac muscle cells, known as pacemaker cells, to automatically generate and regulate the heartbeat. These pacemaker cells possess a unique ability called autorhythmicity, which allows them to reach a threshold potential and fire action potentials spontaneously without requiring any external stimuli. This spontaneous generation of action potentials results in the rhythmic contractions of the heart. The most well-known group of pacemaker cells is located in the sinoatrial (SA) node, and this group is primarily responsible for setting the pace of the entire heart. The heart's pacemaker cells are also influenced by the autonomic nervous system and different hormones that can either increase or decrease the heart rate to maintain blood pressure within optimal ranges.
The pacemaker potential functionally affects the heart rate by determining the interval at which the pacemaker cells depolarize. When these cells depolarize more frequently, the heart rate increases, leading to a faster pumping of the heart. Conversely, when the depolarization rate slows, the heart rate decreases. Therefore, the intrinsic pacemaker activity, modulated by the autonomic nervous system and hormones, is critical for maintaining proper blood flow and pressure throughout the body.